1. Field of the Invention
The invention relates to a golf club head, more particularly to a golf club head which is heavier at a front side of the golf club head.
2. Description of the Related Art
A conventional golf club head is usually made of stainless steel, which has a relatively high density. Therefore, the size of the conventional golf club head is relatively small. It is difficult to design the mass distribution of the ball hitting surface of the conventional golf club head in order to achieve the characteristics of an ideal club head, that is, to achieve the largest inertial moment so as to obtain a longer hitting distance and so as to increase the area of the sweet spot at the ball hitting surface in order to obtain an optimum ball hitting arrangement and better ball control.
Referring to FIGS. 1 and 2, a first example of a conventional golf club head is shown to include a hollow main body (10) that is made of steel and that has a front side (11) for hitting a golf ball. The front side (11) of the conventional golf club head is designed with a thickness of 0.3 cm. in order to provide a substantial degree of hardness and weight thereat. Such an arrangement results in a limited inertial moment which cannot permit a golf ball to travel a longer distance when struck by the golf club head.
To facilitate calculation, it is assumed that the front side of the golf club head is oval-shaped. The mass of the front side (11) is given by the equation: EQU M=p.multidot.V EQU M=p.multidot..pi..multidot.a.multidot.b.multidot.t
wherein "V" is the volume of the hollow main body, "p" is the density of stainless steel (7.8 g./cc), "a" is one-half of the length of the minor axis (3.5/2=1.75 cm), "b"is one-half of the length of the major axis (7.15/2=3.575 cm), and "t" is the thickness of the first side (0.3 cm).
After substituting the above variables into the given equation, the mass of the front side is equal to 45.992 g.
The inertial moment that is provided by the front side (11) of the golf club head when a golf ball is struck is determined as follows: ##EQU1##
Referring to FIGS. 3 and 4, another conventional golf club head is shown to comprise a hollow main body (20) which is made of steel and which has a front side with a wall (22) that defines a cavity. A mass of carbon fiber reinforced resin material (21) (density=1.56 g./cc) fills the cavity and defines a ball hitting surface (23) at the front side. In order to obtain an optimum ball hitting distance, the wall (22) is designed to have a thickness of 0.22 cm, while the mass of resin material (21) is designed to have a thickness of 0.4 cm.
Assuming that the front side of the hollow main body (20) has an oval-shaped cross section. The mass of the front side of the golf club head is computed as follows: ##EQU2##
The inertial moment that is provided by the front side of the golf club head when a golf ball is struck is determined as follows: ##EQU3##
From the above two examples, it is known that the two conventional golf club heads provide the same inertial moment.